The Alkyl Inductive Effect. Calculation of Inductive Substituent Parameters

Levitt, L. S.; Widing, H. F.

doi:10.1002/9780470171912.ch5

Cited by 31 publications

(4 citation statements)

References 65 publications

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“…where s I(L) is Levitt and Widing's inductive scale based on gas-phase ionisation potentials. 11 This results in the regression coefficients and intercept of eqn (4) (R 2 = 0.9787):…”

Section: Resultsmentioning

confidence: 99%

“…E s 0 = À0.31 for n-Pr, n-Bu and n-Pe 27 (see ESIw 2, Table S2)] and the cyclic structure restricts the conformational freedom, and hence the capacity for hindrance, of the polymethylene chain relative to that of linear alkyl groups. Also, the inductive effect is expected to increase regularly with the length of polymethylene chain, similar to that of linear alkyl groups 11 (see ESIw 2.2 and Table S5). The irregular variation of k(x) S /k(n-Pr) 2,S with ring size (see Table 6 and Fig.…”

Section: Dialkyl Substratesmentioning

confidence: 92%

“…compensates for the C-C bond lost and the two C-H bonds gained between the cyclic compound and its acyclic reference. The latter two energies were defined by eqn (11) and eqn (12), respectively. The fragment energies cited in eqn ( 9)-( 12) are given in Table 6.…”

Section: Dialkyl Substratesmentioning

confidence: 99%

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A kinetic investigation, supported by theoretical calculations, of steric and ring strain effects on the oxidation of sulfides and sulfoxides by dimethyldioxirane in acetone

2010

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“…where s I(L) is Levitt and Widing's inductive scale based on gas-phase ionisation potentials. 11 This results in the regression coefficients and intercept of eqn (4) (R 2 = 0.9787):…”

Section: Resultsmentioning

confidence: 99%

Section: Dialkyl Substratesmentioning

confidence: 92%

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A kinetic investigation, supported by theoretical calculations, of steric and ring strain effects on the oxidation of sulfides and sulfoxides by dimethyldioxirane in acetone

2010

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“…With the desired compounds in hand, the k obs for the nornicotine analogues in the aqueous aldol reaction were determined under pseudo-first-order conditions with use of acetone as the donor and 4-nitrobenzaldehyde as the acceptor (Table ). Using the Hammett eq 1, we found that the relationship between the log of the relative rate constant 17 and σ x was linear over the entire domain of tested compounds (ρ = 1.14, R 2 = 0.996) with the exception of 4-Me 2 N (σ = −0.81), which did not have activity over the uncatalyzed aldol reaction (Figure ). Indeed, according to the Hammett equation derived from our data, the substituent on an arylpyrrolidine must have a Hammett value ≥−0.70 before any catalytic activity is observed.…”

mentioning

confidence: 98%

Hammett Correlation of Nornicotine Analogues in the Aqueous Aldol Reaction: Implications for Green Organocatalysis

et al. 2005

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[reaction: see text] A series of meta- and para-substituted 2-arylpyrrolidines were synthesized and examined for their ability to catalyze an aqueous aldol reaction under buffered conditions. Kinetic analysis of arylpyrrolidine-catalyzed reactions displayed a linear Hammett correlation with rho = 1.14 (R(2) = 0.996), indicating that the reaction is accelerated by electron-withdrawing aryl rings. These results show promise for the development of a synthetically viable aqueous organo-catalyst.

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Azomethine, 1‐Azaallyl‐Anionen und metastabile sek. Enamine

et al. 1980

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Die E/Z-Gleichgewichtskonstanten der Keton-anile 6 a -s hangen nicht wesentlich vom induktiven Substituenteneffekt ab. Die fur eine Zuordnung geeigneten ' H-NMR-Verschiebungen gelten auch fur vergleichbare, meist isomerenfreie Azomethine 6 aa-pp und gehorchcn dem Anisotropiemodell. Durch Metallierung entstehen die 1-Azaallyl-Anionen 7; diese werden 'H-NMRspektroskopisch charakterisiert. Kinetische und thcrmodynamische Reaktionslenkung fuhren zu unterschiedlichen Vorzugskonfigurationen dieser Anionen; die Methanolyse liefert metastabile sek. Enamine 8 unter regio-und stereospezifischer N-Protonierung. Aus den €/Z-Gleichgewichtslagen lassen sich weitere Substituentenparameter id abschatzen. Azomethines, 1-Azaallyl Anions, and Metastable Secondary Enamines13*)E / Z equilibrium constants of the ketone anils 6 a -s d o not depend significantly on the inductive substituent effect. ' H NMR chemical shifts used for configurational classification are also effective for assignments in comparable, isomerically almost pure azomethines 6aa-pp and may be explained by the anisotropic shift model. The 1-azaallyl anions 7 prepared by deprotonation are characterized by 'H NMR spectroscopy. Kinetic and thermodynamic control of this metallation reaction result in different preferential configurations of such anions, the methanolysis of which yields metastable sec. enamines 8 by regio-and stereospecific N-protonation. It is possible to estimate further substituent parameters I d from E/Z equilibria. Die €/Z-Gleichgewichtskonstanten von Azomethinen lassen sich mit neuen Substituentenparametern berechnen, deren GroBe anscheinend vorwiegend sterisch bedingt ist*). In der vorliegenden Arbeit untersuchen wir, ob sich der induktive Substituenteneffekt auf die E/Z-Gleichgewichtslage auswirkt. Bei der Deprotonierung dcr Azomethine entstehen synthetisch wichtige 1 -Azaallyl-Anionen, deren Protonenspektren bisher kaurn untersucht wurden. Das in reiner E-Form vorliegende Pinakolon-anil wird auffallend langsani d e p r~t o n i e r t~.~) ; die durch C-Iminoalkylierung3) belegte Metallierung lie0 sich jedoch durch C-Deuterierung nicht sofort nachweisen4). Dies veranlante uns, spektroskopisch nach den Primarurodukten der Protolyse derartiger Anionen zu fahnden. A. SynthesenArylessigsauren 1 (R' = Aryl) stellten wir aus den Chlormethyl-Vorstufen oder aus Acetophenon-Derivaten5) her. Aus ihren Chloriden 2 gewinnt man die monosubstituierten 2-Propanone 3 am besten mit (Ethoxymagnesio)malonester6~7) (Vorschrift A im Exp. Teil). Die alternative Synthese von 3 nach Tiffeeneau*) durch nucleophile Substitution an Chloraceton gelingt

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The Alkyl Inductive Effect. Calculation of Inductive Substituent Parameters

Cited by 31 publications

References 65 publications

A kinetic investigation, supported by theoretical calculations, of steric and ring strain effects on the oxidation of sulfides and sulfoxides by dimethyldioxirane in acetone

A kinetic investigation, supported by theoretical calculations, of steric and ring strain effects on the oxidation of sulfides and sulfoxides by dimethyldioxirane in acetone

Hammett Correlation of Nornicotine Analogues in the Aqueous Aldol Reaction: Implications for Green Organocatalysis

Azomethine, 1‐Azaallyl‐Anionen und metastabile sek. Enamine

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